"Onett Night 1" but it's YET another Hallow's End version
That's right, I'm most likely the first person here on YouTube to upload the full OST of H.S.'s EarthBound/Mother 2 hack named Hallow's End!
This song is a unique piece, which is only heard at the deepest part of Redmont Caves after Sally, Clyde, Craig and you defeated the Avatar of Azathoth. When you exit and re-enter this exact area, the theme somehow doesn't play anymore, and neither could I find it by opening the ROM file in EBMusEd, so congratulations for bumping into this unique piece! :)
I ripped the song by using the steps of the following tutorial: https://youtu.be/rafk1FNYSdU
The picture as used here has been captured by me. Please do not use it without my permission.
This song has originally been composed by Keiichi Suzuki and Hirokazu Tanaka, and was originally edited by H.S. for Hallow's End. Fair use.
Enjoy, like, etc.! :)